Ni-Cr oxide thin films were prepared by the magnetron sputtering with an NiO-Cr
2O
3 composite target and O
2-added Ar sputtering gas. The electric conductivity of the films showed sharp changes from 10
-11 S·m
-1 to 10
0 S·m
-1 with the addition of O
2 gas from 0 vol% to 20 vol%. The existence of the cubic nickel oxide crystal was assured only in the films prepared by the O
2-addition of 20 vol% or less from X-ray diffraction measurements. X-ray photoelectron spectroscopic analysis revealed that the chemical states of chromium and nickel are Cr
2O
3 and Ni
1-xO (0<x<0.34), respectively, and the nickel deficiency maybe increased with the addition of O
2 gas. These results suggested that the Ni
1-xO crystalline particles were embedded in the amorphous Cr
2O
3 matrix. The crystallite size of Ni
1-xO particles increased from 6.3 nm to 32 nm with increase in the O
2-addition ratio from 0 vol% to 20 vol%. The close relationship between the electrical conductivity and the Ni
1-xO particle size of the films brought us to the conclusion that the increase in conductivity was possibly attributable to the crystal growth of the conductive Ni
1-xO crystallites as well as its nickel deficiency.
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